The use of electrosurgical instruments for cutting and/or resecting tissue is highly effective and beneficial for accomplishing precise surgical results. In particular, a cutting electrode of a first instrument is provided with sufficient current to cut through tissue by vaporizing cellular structure in the surgical path of the electrode. Thereafter, in order to stop bleeding, a coagulation electrode of a second instrument and with a lesser magnitude of current is introduced to the surgical path to thereby coagulate transected bleeding blood vessels by desiccation, shrinkage of surrounding tissue, and/or fusion of vessel walls.
Typical prior art electrosurgical devices include a scissor-type forceps-style instrument, as described in U.S. Pat. No. 2,011,169 to Wappler; a double-loop cutting device having a proximal cutting loop connected to a live pole and a distal loop connected to a neutral pole, as described in U.S. Pat. No. 4,060,087 to Hiltebrandt et al.; a single-loop surgical snare device having two electrodes for providing bipolar cauterization, as described in U.S. Pat. No. 5,318,564 to Korth et al.; and a double loop cutting device wherein a proximal cutting loop is un-insulated and a distal insulated support loop having no power supply functions to support and guide the proximal cutting loop, as described in U.S. Pat. No. 5,318,564 to Eggers. Double loop devices having identical power amplitudes to each loop are available for singular cutting or singular coagulating activity.
Each of the above-listed devices has a single power source with a single magnitude of power. Because cutting and coagulation require different power amplitudes or signals, there is no single prior-art instrument capable of accomplishing both events from a single stroke of one instrument through affected tissue. It is therefore apparent that a need is present for such an instrument. Accordingly, and corresponding to disclosure document nos. 371167 filed Feb. 6, 1995, and Feb. 27, 1995, under the Disclosure Document Program of the United States Patent and Trademark Office, a primary object of the present invention is to provide an electrosurgical instrument capable of sequentially cutting and coagulating tissue with a single movement of the instrument through tissue.
Another object of the present invention is to provide an electrosurgical instrument with a cutting electrode having a first current magnitude appropriate for cutting tissue, and a coagulation electrode having a second current magnitude appropriate for coagulating tissue.
Another object of the present invention is to provide an electrosurgical instrument having a cutting electrode and coagulation electrode which are formed having differing cross-sectional configurations specifically adapted to allow the coagulation electrode to follow a cutting electrode and thereby promote rapid coagulation of the tissue.
Another object of the present invention is to provide an electrosurgical instrument with a cutting electrode having a first current magnitude appropriate for cutting tissue, and a coagulation electrode having a second current magnitude appropriate for coagulating tissue.
These and other objects of the present invention will become apparent throughout the description thereof which now follows.